U.S. patent application number 11/204009 was filed with the patent office on 2006-01-12 for method for purifying 5' -protected 2' -deoxypurine nucleosides.
This patent application is currently assigned to MITSUI CHEMICALS, INC.. Invention is credited to Hironori Komatsu, Toshiyuki Kouno, Katsutoshi Tsuchiya.
Application Number | 20060009635 11/204009 |
Document ID | / |
Family ID | 18965005 |
Filed Date | 2006-01-12 |
United States Patent
Application |
20060009635 |
Kind Code |
A1 |
Komatsu; Hironori ; et
al. |
January 12, 2006 |
Method for purifying 5' -protected 2' -deoxypurine nucleosides
Abstract
A method for efficiently purifying 5' protected 2'-deoxypurine
nucleosides, efficient production of which has previously been
difficult. Impurities can be separated by obtaining the 5'
protected 2'-deoxypurine nucleoside as an inclusion crystal
including a solvent such as that having a nitrile structure in
order to purify the 5' protected 2'-deoxypurine nucleoside at a
high purity. This invention enables synthesis of highly purified,
protected deoxypurine nucleosides easily on a large scale, which
has previously been performed by column chromatography method.
Inventors: |
Komatsu; Hironori;
(Mobara-shi, JP) ; Kouno; Toshiyuki; (Mobara-shi,
JP) ; Tsuchiya; Katsutoshi; (Mobara-shi, JP) |
Correspondence
Address: |
BUCHANAN INGERSOLL PC;(INCLUDING BURNS, DOANE, SWECKER & MATHIS)
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
MITSUI CHEMICALS, INC.
Tokyo
JP
|
Family ID: |
18965005 |
Appl. No.: |
11/204009 |
Filed: |
August 16, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10120500 |
Apr 12, 2002 |
6958391 |
|
|
11204009 |
Aug 16, 2005 |
|
|
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Current U.S.
Class: |
536/27.1 ;
536/28.1 |
Current CPC
Class: |
C07H 1/06 20130101; C07H
19/16 20130101 |
Class at
Publication: |
536/027.1 ;
536/028.1 |
International
Class: |
C07H 19/22 20060101
C07H019/22; C07H 19/048 20060101 C07H019/048 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2001 |
JP |
2001-113835 |
Claims
1.-9. (canceled)
10. An inclusion compound represented by the following formula (5)
##STR6## wherein R1 represents a 4-methoxytrityl group,
4,4'-dimethoxytrityl group or triphenylmethyl group, B represents a
purine group wherein an amino group is protected, m and n are
independently an integer, and R3 is a lower alkyl group or an aryl
group.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of application Ser. No.
10/120,500, filed on Apr. 12, 2002, which claims the benefit of
Japanese Patent Application No. 2001-113835 filed on Apr. 12, 2001,
the contents of such applications being incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method of purifying
5'-protected 2'-deoxypurine nucleoside and a derivative thereof, as
well as solvent-inclusion compounds thereof obtained by the method.
More specifically, the present invention relates to a method of
purifying 5'-protected 2'-deoxypurine nucleosides useful for
producing them as well as a solvent inclusion compounds of
5'-protected 2'-deoxypurine nucleosides which are obtained by the
purification method.
DESCRIPTION OF THE RELATED ART
[0003] 5'-protected 2'-deoxy-.beta.-purine nucleosides are
compounds useful as raw materials for antisense DNA or the like,
which has recently been developed.
[0004] In recent years, with developments in manufacturing genomic
drugs, antisense DNA drugs or the like have rapidly been developed.
Therewith, a DNA oligomer used as a raw material, and further,
protected deoxy nucleosides used as raw materials for the oligomer
are increasingly demanded. Regarding the pharmaceutical uses, it is
necessary to use an extremely highly purified intermediate product
to reduce generation of by-products based on impurities to a
minimum.
[0005] As is clear from Japanese Patent Laid-Open Nos. 58-180500
and 63-179889, National Publication of International Patent
Application No. 6-507883, etc., 5'-protected deoxypurine
nucleosides have been purified by column chromatographic method
till now. By this method, separation of impurities greatly
different in their polarities or structures may be carried out
relatively easily, but elimination of impurities having a similar
structure is difficult. In particular, there are many cases where
it is difficult to eliminate a 3'-substituted isomer that is a
especially problematic impurity. In addition, since this method
needs a large-scale purification device, in view of mass production
and mass supply in the future, it cannot help saying that this
method has a large problem.
[0006] Up till now, studies regarding elimination of impurities
without using column chromatography have been made. Specifically,
purification by reprecipitation method is disclosed in Japanese
Patent Laid-Open No. 60-152495 and a PCT application, WO200075154.
The reprecipitation method is a method in which, after a crude
compound is dissolved in a soluble solvent, the compound is
compulsively reprecipitated by addition of an insoluble solvent or
dropping into an insoluble solvent. Consequently, its purification
ability is basically low. Moreover, it is industrially difficult to
appropriately control the amount ratio between the soluble solvent
and the insoluble solvent. In addition, where the amount ratio of
these solvents is set inappropriately, it easily results in
oilification or generates a viscous precipitate so that
purification is apt to end in failure. Actually, according to a
method described in Japanese Patent Laid-Open No. 60-152495, in
some cases, the purified product is obtained as a viscous syrupy
substance, and, from an industrial viewpoint, this is a problem.
Although some methods of forming an amorphous product by
reprecipitation have been disclosed till now, no methods for
obtaining a crystal by crystallization or recrystallization are
known.
SUMMARY OF THE INVENTION
[0007] The present invention has been completed in view of the
conventional problems, and the object of the present invention is
to provide a purification method, which is efficient and does not
need special facilities by which extremely highly purified
5'-protected 2'-deoxypurine nucleosides can be obtained.
[0008] As a result of intensive studies by the present inventors
directed toward the above object, it has been found that, using a
nitrile solvent such as acetonitrile, 5'-protected 2'-deoxypurine
nucleosides can be obtained as a crystal that includes the solvent,
and then it can be purified by a purification method using
crystallization or recrystallization, thereby completing the
present invention.
[0009] Thus, the present invention includes the following
embodiments:
[0010] (1) A method of purifying a 5'protected 2'-deoxypurine
nucleoside, which comprises the steps of:
[0011] obtaining a compound represented by the following formula
(1): ##STR1## wherein R.sup.1 represents a 4-methoxytrityl group,
4,4'-dimethoxytrityl group or triphenylmethyl group, and B
represents a purine group wherein an amino group is protected; in
the form of inclusion crystals including a solvent, in a liquid
medium comprising the solvent for inclusion; and
[0012] recovering the inclusion crystals from the liquid
medium.
[0013] (2) A method of purifying a 5'protected 2'-deoxypurine
nucleoside according to the above section (1), wherein the solvent
for inclusion is a nitrile compound substituted by a lower alkyl
group or an aryl group.
[0014] (3) A method of purifying a 5'protected 2'-deoxypurine
nucleoside according to the above section (2), wherein the solvent
for inclusion is acetonitrile.
[0015] (4) A method of purifying a 5'protected 2'-deoxypurine
nucleoside according to any one of the above sections (1) to (3),
wherein a crude preparation comprising the compound of the formula
(1) and a compound of the following formula (2): ##STR2## wherein
R.sup.2 represents a hydrogen atom, 4-methoxytrityl group,
4,4'-dimethoxytrityl group or triphenylmethyl group, and R.sup.1
and B have the same definitions as stated above; is dissolved in
the liquid medium and the compound of the formula (2) is removed
into the liquid medium by recovering the compound of the formula
(1) in the form of inclusion crystals from the liquid medium.
[0016] (5) A method of purifying a 5'protected 2'-deoxypurine
nucleoside according to any one of the above sections (1) to (4),
wherein the compound of the formula (1) is a compound of the
following formula (3) ##STR3## or a compound of the following
formula (4) ##STR4##
[0017] (6) A method of purifying a 5'protected 2'-deoxypurine
nucleoside according to any one of the above sections (1) to (5),
wherein the inclusion crystals of the compound of the formula (1)
including the solvent for inclusion are recrystalized from a liquid
medium consisting of the solvent for inclusion.
[0018] (7) A method of purifying a 5'protected 2'-deoxypurine
nucleoside according to any one of the above sections (1) to (6),
wherein the liquid medium consisting of a single solvent for
inclusion.
[0019] (8) An inclusion compound represented by the following
formula (5) ##STR5##
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] The present invention will be described in detail below.
[0021] The purine group forming the B in the formula (1) means a
nucleic acid purine base of a natural or a unnatural nucleoside.
Specific examples include adenine and guanine.
[0022] Examples of a protecting group for the amino group of the
purine group include an alkyl group, an alkylacyl group and a
benzoyl group.
[0023] The alkyl group may be straight chained or branched, or
another functional group may be added thereto, as far as the
function as the protecting group can be maintained. Examples of the
alkyl group include a methyl group, an ethyl group, ann-propyl
group, a2-propyl group, ann-butyl group, aniso-butyl group,
etc.
[0024] The alkylacyl group may be straight chained or branched, or
may form a ring, or another functional group may be added thereto,
as far as the function as the protecting group can be maintained.
Examples of the alkylacyl group include an acetyl group, a
propionyl group, an n-butyryl group, an iso-butyryl group, a
pivaloyl group, an n-pentyloyl group, an iso-pentyloyl group, a
cyclopropylcarbonyl group, a phenoxyacetyl group, etc.
[0025] The benzoyl group may not be substituted or may be
substituted as far as the function as the protecting group can be
maintained. One substituent may be at any one of positions 2, 3 and
4 of a phenyl group. Moreover, the substituent may be at a
plurality of positions. Examples of the substituents include an
alkyl group such as a methyl group, an ethyl group, a 2-propyl
group, an n-butyl group or a tert-butyl group; a hydroxyl group; an
alkyloxy group such as a methoxy group, an ethoxy group, an
n-propyloxy group, a 2-propyloxy group or an n-butyloxy group; a
nitro group; a halogen group such as a fluoro group, a chloro
group, a bromo group or an iodo group; an amino group; an
alkylamino group such as a methylamino group, an ethylamino group,
an n-propylamino group, a dimethylamino group, a diethylamino group
or a diisopropylamino group; an acyl group such as an acetyl group,
a propionyl group or a benzoyl group; a phenyl group; a pyridinyl
group, etc.
[0026] Specific examples of the benzoyl groups include a benzoyl
group, a 2-chlorobenzoyl group, a 3-chlorobenzoyl group, a
4-chlorobenzoyl group, a2-bromobenzoyl group, a3-bromobenzoyl
group, a 4-bromobenzoyl group, a 2-fluorobenzoyl group, a
3-fluorobenzoyl group, a 4-fluorobenzoyl group, a 2-methoxybenzoyl
group, a 3-methoxybenzoyl group, a 4-methoxybenzoyl group, a
2-nitrobenzoyl group, a 3-nitrobenzoyl group, a4-nitrobenzoyl
group, a2-aminobenzoyl group, a 3-aminobenzoyl group, a
4-aminobenzoyl group, a 2-methylaminobenzoyl group, a
3-methylaminobenzoyl group, a 4-methylaminobenzoyl group, a
2-dimethylaminobenzoyl group, a 3-dimethylaminobenzoyl group, a
4-dimethylaminobenzoyl group, a 4-phenylbenzoyl group, a
4-acetylbenzoyl group, etc.
[0027] Examples of a nitrile compounds substituted by a lower alkyl
group or aryl group for formation of inclusion crystals, include
acetonitrile, propionitrile, n-butyronitrile, iso-butyronitrile,
n-pentanenitrile, n-hexanenitrile, benzonitrile, etc. At least one
of these nitrile compounds may be used.
[0028] The liquid medium for formation of the inclusion crystals
may be composed either only of the solvent to be included in the
crystals or of a mixture of the solvent for inclusion and other
solvent(s) which does not form inclusion crystals at a ratio
capable of mixing. Examples of the other solvents capable of being
mixed with the solvent for inclusion include alcohols such as
methanol, ethanol and isopropanol; esters such as ethyl acetate and
butyl acetate; ketones such as acetone, methylethylketone and
methylisobutylketone; ethers such as diethyl ether, diisopropyl
ether, dioxane and tetrahydrofuran (THF); aromatic hydrocarbons
such as benzene, toluene, cumene, xylene, mesitylene,
diisopropylbenzene and triisopropylbenzene; halogenated
hydrocarbons such as dichloromethane, chloroform and
dichloroethane; pyridines such as pyridine, lutidine and quinoline;
tertiary amines such as triethylamine and tributylamine; polar
solvents such as dimethylformamide (DMF), dimethyl imidazolidinone
(DMI) and dimethyl sulfoxide (DMSO); water etc. At least one of
these solvents may be used as the other solvent. The mixing ratio
of the above listed other solvent(s) is 100% by weight or less with
respect to the solvent for inclusion, preferably 20% by weight or
less, and more preferably 10% by weight or less.
[0029] The term "inclusion crystal" including a solvent is herein
used to mean that a solvent plays an auxiliary role to form a
crystal structure, such that a crystal is formed in a form wherein
a solvent is taken up into a crystal lattice thereof, or a complex
is formed by a weak interaction between a crystal and a solvent.
The inclusion form and the crystal structure are not particularly
limited.
[0030] The amount of a nitrile solvent in crystallization and
recrystallization are not particularly limited, as far as the
amount is below the saturation solubility of a compound to be
purified to the solution, but desirably the amount of the solvent
is 5 times by weight or more to 150 times by weight or less of the
amount of the compound of the formula (1), and further desirably it
is 8 times by weight or more to 50 times by weight or less of the
amount of the compound of the formula (1).
[0031] A temperature for crystallization and recrystallization are
not particularly limited, but a temperature within a range from
-10.degree. C. to the boiling point of a solvent or a liquid medium
is desired. Generally, purification can be performed more
sufficiently by a single time of recrystallization, but
purification at higher purity can also be realized by performing
recrystallization repeatedly. A preferable liquid medium for
recrystallization is that consisting of a solvent for inclusion
alone and it is more preferable to use the same single solvent for
inclusion in both of crystallization and recrystallization.
[0032] As stated above, according to the present invention, it
becomes possible to efficiently purify protected 5' protected
2'-deoxypurine nucleosides.
EXAMPLES
[0033] The present invention will be further specifically described
in the following examples. The examples are not intended to limit
the scope of the invention.
Example 1
Production of a
N2-isobutyryl-5'-O-(4,4'-dimethoxytrityl)-2'-deoxyguanosine and
acetonitrile (2:1) complex
[0034] 110 g (95% content) of N2-isobutyryl-2-deoxyguanosine was
subjected to azeotropic dehydration with pyridine, and then
dissolved in 2.4 L of pyridine. After adding 118.3 g of
4,4'-dimethoxytrityl chloride at room temperature, the mixture was
stirred at room temperature for 3 hours. After neutralizing
hydrochloric acid with sodium bicarbonate, the reaction solution
was concentrated to about 400 g. After adding 1.5 L of ethyl
acetate and 1.5 L of water were added thereto, the mixed solution
was separated, and then washing with water was repeatedly performed
until no N2-isobutyryl-2-deoxyguanosine as a raw material was found
in an organic layer thereof. After washing with 1 kg of 20% sodium
chloride solution, drying with sodium sulfate was performed. After
performing filtration, a solvent was removed and ethyl acetate was
then added so that the total amount became 700 g.
[0035] This solution was dropped into 3,200 g of diisopropyl ether,
while intensively stirring, and thereafter the obtained solution
was stirred at room temperature for 2 hours. The solid obtained by
filtration was subjected to vacuum drying at 50.degree. C., and
after confirming that a constant weight was obtained, it was
dissolved in 4.4 L of acetonitrile at room temperature. After
stirring at room temperature for 4 hours, the deposited solid was
filtrated. The obtained product was subjected to vacuum drying at
room temperature for 4 hours and then an NMR analysis. It was found
by the analysis that the obtained product included 2 molecules of
acetonitrile. Where vacuum drying was performed at 40.degree. C.
for 12 hours, it was found by the subsequent NMR analysis that the
obtained product included one molecule of acetonitrile.
[0036] Where vacuum drying was performed at 50.degree. C. for 15
hours, it was found by the subsequent NMR analysis that the
obtained product included 0.67 molecule of acetonitrile. Further,
where vacuum drying was performed at 55.degree. C. until a constant
weight was obtained (for 24 hours), it was found by the subsequent
NMR analysis that the obtained product included 0.5 molecule of
acetonitrile. By X-ray diffraction (XRD), it was found that the
obtained product was a crystal in any of the above dry conditions.
Moreover, by TG-DTA analysis, it was found that, regarding a
crystal included 0.5 molecule of acetonitrile that was obtained by
drying until a constant weight was obtained, the weight of the
crystal was not reduced until a temperature was raised to the
temperature for endothermic reaction (81.degree. C. to 93.degree.
C.), the crystal having no attached solvent. The yield was 168 g
(yield rate 84.8%). As a result of an analysis by HPLC (UV 254 nm),
the purity was 99.7% by area. The largest impurity was
N2-isobutyryl-3',5'-O-bis(4,4'-dimethoxytrityl)-2'-deoxyguanosine
(0.17% by area).
[0037] NMR (DMSO-d.sub.6) .delta.: 12.1 (s, 1H) , 11.7 (s, 1H) ,
8.1 (s, 1H), 7.3 (m, 2H), 7.3-7.3 (m, 7H), 6.9-6.8 (m, 4H), 6.3 (t,
J=6 Hz, 1H), 5.4 (m, 1H), 4.4 (m, 1H), 3.97 (m, 1H), 3.724 (s, 3H),
3.719 (s, 3H), 3.2 (m, 1H), 3.1 (m, 1H), 2.8 (m, 1H), 2.4 (m, 1H),
2.1 (s, 3/2H, acetonitrile), 1.1 (d, J=6.8 Hz, 6H).
[0038] .sup.1R(KBr) cm.sup.-1: 3398, 3238, 2935, 2838, 1679, 1609,
1561, 1509, 1252, 1178, 1034, 830 (Absorption of acetonitrile
derived from nitrile was weak and was not observed.)
Example 2
Production of
N6-benzoyl-5'-O-(4,4'-dimethoxytrityl)-2'-deoxyadenosine
[0039] 45.0 g (0.127 mol) of N6-benzoyldeoxyadenosine was dissolved
in 500 ml of pyridine followed by azeotropic dehydration, and then
the obtained product was dissolved in 500 ml of pyridine. While
stirring, 42.9 g (0.127 mol) of 4,4'-dimethoxytrityl chloride was
added thereto, and the mixture was further stirred at room
temperature for 2.5 hours. After 12.8 g of sodium bicarbonate was
added thereto and the mixture was stirred at room temperature for
30 minutes, a solvent was removed at reduced pressure. To the
residue, 830 ml of methylisobutylketone was added, and while
stirring 830 ml of water was further added thereto followed by
stirring for 10 minutes. Subsequently, an organic layer thereof was
collected, washed with a saturated saline solution and dried with
sodium sulfate, and thereafter a solvent was removed at reduced
pressure. The residue was dropped in 800 ml of diisopropyl ether
that was intensively stirred, and the generated precipitate was
collected by filtration.
[0040] The precipitate was recrystallized from 750 ml of
acetonitrile, and the crystal product was collected by filtration.
As a result of an NMR analysis, the product included one molecule
of acetonitrile. When the crystal product was subjected to vacuum
drying, acetonitrile was lost. The weight was 66.7 g. When the
obtained product was analyzed by high performance liquid
chromatography [ODS: octadecyl silica gel column,
acetonitrile/water (8:2)], using a UV detector (254 nm), the purity
was 99.5%. The yield of
N6-benzoyl-5'-O-(4,4'-dimethoxytrityl)-2'-deoxyadenosine was 79.4%.
The largest impurity was
N6-benzoyl-3',5'-O-bis(4,4'-dimethoxytrityl)-2'-deoxyadenosine
(0.15% by area).
Reference Example 1
Production of
N2-isobutyryl-3',5'-O-bis(4,4'-dimethoxytrityl)-2'-deoxyguanosine
[0041] After the filtrate obtained by the recrystallization in
Example 1 was concentrated, the concentrate residue was purified by
column chromatography (ethyl acetate/hexane). The purified fraction
was concentrated to obtained a yellow oily product. The yellow oily
product was then dropped into diisopropyl ether and the precipitate
thus formed was recovered by filtration and dried, whereby the
titled compound was obtained as a light yellow powder.
[0042] .sup.1H NMR(400 MHz,DMSO-d.sub.6) .delta. 12.1(1H,s),
11.5(1H,s), 7.9(1H,s), 7.5-7.2(18H,m), 6.8(8H,m), 6.2(1H,m),
4.4(1H,m), 3.8(1H,m), 3.7(12H,s), 3.6(1H,m), 3.0(1H,m), 2.8(1H,m),
2.4(1H,m), 1.8(1H,m), 1.1(6H,m), 1.0(6H,m)
Reference Example 2
Production of
N2-isobutyryl-5'-O-(tert-butyldimethylsilyl)-2'-deoxyguanosine
[0043] N2-isobutyryl-2'-deoxyguanosine (20.5 g) was dissolved in
200 ml of DMF. After 18.5 g of imidazole was dissolved in the
resultant solution by addition, 21.4 g of tert-butyldimethylsilyl
chloride was then added. DMF (100 ml) was further added and the
solution was stirred at room temperature. After 8 hours, extraction
using chloroform was carried out and the organic layer was washed
by a saturated aqueous solution of sodium chloride and dried with
anhydrous magnesium sulfate. After concentration of the extract,
the target compound was separated by column chromatography
(methanol/chloroform). The fraction solution including the target
compound was prepared and concentrated to obtain 20.5 g of the
titled compound (yield; 74%).
[0044] .sup.1H NMR(400 MHz,CDCl.sub.3) .delta.:12.4(1H,s),
10.9(1H,s), 8.0(1H,s), 6.0(1H,dd,J=6.4,6.4 Hz), 4.6(2H,m),
4.1(1H,d,J=2.0 Hz), 3.8(2H,m), 2.9(1H,m), 2.4(2H,m), 1.3(6H,m),
0.8(9H,s), 0.02(6H,s)
Reference Example 3
Production of
N2-isobutyryl-5'-O-(tert-butyldimethylsilyl)-3'-O-(4,4'-dimethoxytrityl)--
2'-deoxyguanosine
[0045]
N2-isobutyryl-5'-O-(tert-butyldimethylsilyl)-2'-deoxyguanosine
(19.8 g) was dissolved in 100 ml of anhydrous pyridine.
4,4'-dimethoxytrityl chloride (1.66 g) was added to the resultant
solution and 140 ml of anhydrous pyridine was further added, follow
by stirring at 40.degree. C. After the reaction completed, the
reaction mixture was neutralized by sodium hydrogen carbonate and
pyridine was distilled off. Extraction using chloroform was carried
out and the extract was washed by a saturated aqueous solution of
sodium chloride and dried with anhydrous magnesium sulfate. The
extract was concentrated and purified by column chromatography
(ethyl acetate/hexane) to obtain 25.8 g of the titled compound
(yield: 78%).
[0046] .sup.1H NMR(400 MHz,CDCl.sub.3) .delta.: 11.9(1H,s),
8.1(1H,s), 7.8(1H,s), 7.5-7.2(9H,m),6.8(4H,m),6.2(1H,dd,J=6.0,8.4
Hz),4.4(1H,m), 4.1(1H,m), 3.8(6H,s), 3.6(1H,dd,J=8.8,11.2 Hz),
3.3(1H,dd,J=2.8,11.2 Hz),2.6(1H,m),2.0-1.6(2H,m),1.3(6H,m),
0.8(9H,s), 0.02(6H,s)
Reference Example 4
Production of
N2-isobutyryl-3'-O-(4,4'-dimethoxytrityl)-2'-deoxyguanosine
[0047] N2-isobutyryl-3'-O(4,4'-dimethoxytrityl)-2'-deoxyguanosine
(25 g) was dissolved in 200 ml of dry THF. A THF solution (40 ml)
of tetrabutylammonium fluoride was added to the resultant solution
and 100 ml of dry THF was further added, followed by stirring at
room temperature. After 8 hours, extraction using chloroform was
carried out, and the extract was washed by a saturated solution of
sodium chloride and dried with anhydrous magnesium sulfate. The
extract was then concentrated and purified by column chromatography
(ethyl acetate/hexane/methanol) to obtain 12.9 g of the titled
compound as a white powder (yield: 60%).
[0048] .sup.1H NMR (400 MHz, CDCl.sub.3) .delta..quadrature. 12.0
(1H, s), 8.3 (1H, s), 7.7 (1H, s), 7.5-7.2(9H,m), 6.8(4H,m),
6.2(1H,dd,J=5.2, 10 Hz), 4.5(1H,m), 4.0(1H,m), 3.8(6H,s),
3.7(1H,m), 3.3(1H,m), 2.6(1H,m), 2.4(1H,m), 1.7(1H,m),
1.2(6H,m)
Comparative Example 1
[0049] In respect of an ability to eliminate impurities such as the
3'-substituted isomer
[N2-isobutyryl-3'-O-(4,4'-dimethoxytrityl)-2'-deoxyguanosine] or
the 3',5'-multiple substituted form
[N2-isobutyryl-3',5'-o-bis(4,4'-dimethoxytrityl)-2'-deoxyguanosine],
there was made a comparison between a method involving
recrystallization with an acetonitrile solvent and a purification
method involving reprecipitation using dichloromethane as a soluble
solvent, and hexane or toluene as an insoluble solvent. In
addition, the yield rate of a product of interest,
[0050]
[N2-isobutyryl-5'-O-(4,4'-dimethoxytrityl)-2'-deoxyguanosine], was
compared between both methods, and also thermal analysis (DSC:
endothermic peak, endothermic energy) of the obtained crystal was
carried out. The results thus obtained are shown in Table 1, which
include the contents of the 3'isomer and the multi-substituted
compound in the crude crystal preparation, and the crystals after
recrystalization using each solvent. TABLE-US-00001 TABLE 1
Purification solvent Dichloro- Dichloro- Rough Acetoni- methane/
methane/ crystal trile hexane toluene 3'-isomer 4.9% 0.08% 3.06%
0.76% Multiple 2.76% 0% 2.27% 0.36% substituted form Yield rate 95%
83% 76% Endothermic 81.degree. C. No clear endothermic peak peaks
were shown. Endothermic 28 J/g energy (% is based on weight.)
[0051] As is clear from the results concerning DSC, it was revealed
that, since the endothermic peaks of the compounds were different,
the crystal types of the compounds were also different. Regarding
the large endothermic energy, it was further revealed that the
product obtained from acetonitrile alone was formed as
crystals.
Reference Example 5
Production of
N6-benzoyl-3',5'-O-bis(4,4'-dimethoxytrityl)-2'-deoxyadenosine
[0052] After the filtrate obtained by the recrystallization in
Example 2 was concentrated, the concentrate residue was purified by
column chromatography (ethyl acetate/hexane). The purified fraction
was concentrated to obtained a yellow oily product. The yellow oily
product was then dropped into diisopropyl ether and the precipitate
thus formed was recovered by filtration and dried, whereby the
titled compound was obtained as a light yellow powder.
[0053] .sup.1H NMR(400 MHz,DMSO-d6).delta.:11.2(1H,br), 8.6(1H,s),
8.5(1H,s), 8.0(2H,m), 7.7-6.7(29H,m), 6.4(1H,m), 4.3(1H,m),
4.1(1H,m), 3.8(14H,s), 3.6(1H,m), 3.0(1H,m), 1.0(6H,m)
Reference Example 6
Production of
N6-benzoyl-5'-O-(tert-butyldimethylsilyl)-2'-deoxyadenosine
[0054] N6-benzoyl-2'-deoxyadenosine (20.95 g) was dissolved in 200
ml of DMF. Imidazole (15.7 g) was dissolved to the resultant
solution by addition. Then, 20.8 g of tert-butyldimethylsilyl
chloride was added. DMF (100 ml) was further added and the solution
was stirred at room temperature. After 8 hours, extraction using
chloroform was carried out and the organic layer was washed by a
saturated aqueous solution of sodium chloride and dried with
anhydrous magnesium sulfate. After concentration of the extract,
the target compound was purified by column chromatography
(methanol/chloroform) to obtain 16.1 g of the titled compound
(yield; 61%).
[0055] .sup.1H NMR(400 MHz,CDCl.sub.3) .delta.:9.1(1H,s),
8.8(1H,s), 8.3(1H,s), 8.0(2H,d,J=12.4 Hz), 7.6-7.5(3H,m),
6.6(1H,dd,J=6.8,6.8 Hz), 4.7(1H,m), 4.1(1H,m), 3.9(2H,m),
2.8(1H,m), 2.6(1H,m), 0.9(9H,s), 0.1(6H,s)
Reference Example 7
Production of
N6-benzoyl-5'-O-(tert-butyldimethylsilyl)-3'-O-(4,4'-dimethoxytrityl)-2'--
deoxyadenosine
[0056] N6-benzoyl-5'-O-(tert-butyldimethylsilyl)-2'-deoxyadenosine
(16.1 g) was dissolved in 100 ml of anhydrous pyridine.
4,4'-dimethoxytrityl chloride (12.8 g) and anhydrous pyridine (140
ml) were further added, follow by stirring at 45.degree. C. After
the reaction completed, the reaction mixture was neutralized by
sodium hydrogen carbonate, and pyridine was distilled off.
Extraction using chloroform was carried out and the extract was
washed by a saturated aqueous solution of sodium chloride and dried
with anhydrous magnesium sulfate. The extract was concentrated and
then purified by column chromatography (ethyl acetate/hexane) to
obtain 16.7 g of the titled compound (yield: 63%).
[0057] .sup.1H NMR(400 MHz,CDCl.sub.3) .delta.:9.1(1H,s),
8.9(1H,s), 8.3(1H,s), 8.1(2H,d,J=7.2 Hz), 7.7-7.3(12H,m),
6.9(4H,m), 6.7(1H,dd,J=5.6,8.4 Hz), 4.5(1H,m), 4.2(2H,m),
3.9(6H,s), 3.7(1H,dd,J=2.4,11.2 Hz), 3.4(1H,dd,J=8.4,11.2 Hz),
2.2-2.1(2H,m), 2.0-1.6(2H,m), 1.3(1.5H,m), 0.9(9H,s),
0.03(6H,s)
Reference Example 8
Production of
N6-benzoyl-3'-O-(4,4'-dimethoxytrityl)-2'-deoxyadenosine
[0058]
N6-benzoyl-5'-O-(tert-butyldimethylsilyl)-3'-O-(4,4'-dimethoxytrit-
yl)-2'-deoxyadenosine (16.2 g) was dissolved in 200 ml of dry THF.
A THF solution (31 ml) of tetrabutylammonium fluoride was added to
the resultant solution and 100 ml of dry THF was further added,
followed by stirring at room temperature. After 8 hours, THF was
distilled off and extract ion using chloroform was carried out. The
extract was then washed by a saturated solution of sodium chloride
and dried with anhydrous magnesium sulfate. The extract was then
concentrated and purified by column chromatography
(ethylacetate/hexane/methanol) to obtain 13.8 g of the titled
compound as a white powder (yield: 98%).
[0059] .sup.1H NMR(400 MHz,CDCl.sub.3) .delta.:9.0(1H,br),
8.7(1H,s), 8.1(1H,s), 8.0(2H,m), 7.7-7.2(12H,m), 6.9(4H,m),
6.4(1H,m), 4.6(1H,m), 4.1(1.3H,m), 3.8(6H,s), 3.7(1H,m), 3.3(1H,m),
2.7(1H,m), 2.0(2H,m), 2.0-1.6(2H,m), 1.7(1H,m), 1.3(2H,m)
Comparative Example 2
[0060] In respect of an ability to eliminate impurities such as the
3'-substituted isomer
(N6-benzoyl-3'-O-(4,4'-dimethoxytrityl)-2'-deoxyadenosine) or the
3',5'-multiple substituted form
[N6-benzoyl-3',5'-O-bis(4,4'-dimethoxytrityl)-2'-deoxyadenosine),
there was made a comparison between a method involving
recrystallization with an acetonitrile solvent and a purification
method involving reprecipitation with dichloromethane as a soluble
solvent and a mixed solution of t-butylmethyl ether and hexane
(1:2) as an insoluble solvent. In addition, the yield rate of a
product of interest,
[N6-benzoyl-5'-O-(4,4'-dimethoxytrityl)-2'-deoxyadenosine], was
compared between both methods, and also thermal analysis (DSC:
endothermic peak, endothermic energy) of the obtained crystal was
carried out.
[0061] The results thus obtained are shown in Table 2, which
include the contents of the 3'isomer and the multi-substituted
compound in the crude crystal preparation, and the crystals after
recrystalization using each solvent. TABLE-US-00002 TABLE 2
Purification solvent Dichloromethane/ Rough Acetoni- t-butylmethyl
crystal trile ether-hexane (1:2) 3'-isomer 1.84% 0.06% 2.24%
Multiple 4.03% 0% 1.43% substituted form Yield rate 87% 96%
Endothermic peak 114.degree. C. 125.degree. C. Endothermic energy
34 J/g (% is based on weight.)
[0062] As is clear from the results concerning DSC, it was revealed
that, since the endothermic peaks of the compounds were different,
the crystal types of the compounds were also different. Regarding
the large endothermic energy, it was further revealed that the
product obtained from acetonitrile alone was formed as
crystals.
[0063] The condition of HPLC for each compound is as follows: (1)
HPLC conditions in Comparative Examples 1 and 2 (analysis of the
amount of the multiple substituted form):
[0064] Column: Develosil TMS-UG-5 [0065] 150 mm.times..phi.4.6
[0066] Flow rate: 1.0 mL/min
[0067] Column temperature: 40.degree. C.
[0068] Detection wavelength: 254 nm
[0069] Mobile phase: gradient conditions TABLE-US-00003 Time (min)
Liquid B (%) 0 20 15 70 35 100 40 100 45 20 60 STOP
[Liquid A]
[0070] 100 mL of 100 mM triethylamine-acetic acid (pH7)/880 mL of
water/20 mL of acetonitrile
[Liquid B]
[0071] 100 mL of 100 mM triethylamine-acetic acid (pH7)/900 mL of
acetonitrile
[0072] (2) HPLC conditions in Comparative Examples 1 and 2
(analysis of the amount of the 3'-isomer):
[0073] Column: Develosil TMS-UG-5 [0074] 150 mm.times..phi.4.6
[0075] Mobile phase: acetonitrile-water (55:45)
[0076] Flow rate: 1.0 mL/min
[0077] Column temperature: 40.degree. C.
[0078] Detection wavelength: 254 nm
[0079] Conditions for thermal analysis: [0080] Apparatus: DSC-7
(PerkinElmer) [0081] Rate of temperature rise: 10.degree.
C./min
[0082] Condition for XRD: [0083] Apparatus: RAD-RVC (RIGAKU) [0084]
X-ray target: Cu 50 kV 200 mA
[0085] According to the present invention, a method capable of mass
production enables production of highly purified protected
2'-deoxypurine nucleosides more efficiently than conventional
methods.
* * * * *